1. Field of the Invention
The present invention relates generally to insect control systems and vapor exhaust systems for structures, and more particularly, but not by way of limitation, to an improved system for both selectively injecting pesticide beneath a structure and extracting fluids, such as water and harmful vapors from beneath the structure.
2. Brief Description of the Related Art
Numerous systems have been proposed for protecting buildings and homes from damage caused by pests, such as subterranean termites, which can do considerable structural and cosmetic damage over time. A common practice for treating infestation of pests into a structure is to pretreat the ground under the structure with pesticide chemicals during the construction process. This is done by applying a substantial quantity of pesticides, such as termiticide, on the ground under the proposed structure before the slab is poured in an attempt to create a chemical barrier that will keep the insects from entering the structure.
The problem with this method of treatment is the amount of pesticide required to be used can be harmful to occupants of the structure as well as harmful to the ground water. Furthermore, even though a large amount of pesticide is applied to the ground, the resulting chemical barrier nevertheless becomes ineffective over time as the chemicals break down.
With these problems in mind, other methods have been developed for the periodic injection of pesticide beneath structures. One particular method involves the drilling of holes in and around the slab for the injection of pesticide. This method has many drawbacks which include affecting the integrity of the slab, the mess of drilling through the slab, convenience of having to clear a path around the structure to permit access for the drilling, the need for the holes to be plugged, and the residual odor of the pesticide that escapes during the injection process. In addition, this process must be periodically repeated during the lifetime of the structure.
Considerable efforts have been made to alleviate the problems of post construction periodic injection of pesticides beneath the structure by placing a injection system beneath the structure during the construction process. Many of these systems involve placing a network of porous tubing beneath the structure. The problem encountered in these systems however is that the holes provided in the tubing have a fixed diameter and thus are susceptible to clogging. That is, because the preference to place the network of tubing within the fill material positioned under the slab, the fill material often obstructs or clogs the holes. The holes can also get clogged by dead insects and other pests that may enter the holes in the tubing over the course of the lifetime of the system. When the holes become clogged or obstructed, they fail to deliver pesticide to the surrounding location, thereby creating a gap in the chemical barrier which can be exploited by pests.
Other injection network systems with fixed holes have attempted to prevent hole obstruction elaborate systems or by varying construction procedures. For example, systems have been developed where the holes are sheltered with wick-like membranes, soil screens, shower-type sprinkler heads, and sponges. Other systems attempt to keep the holes from being obstructed by surrounding the holes with specialized fill materials applied during the construction process. Each of these types of systems is complex and increases installation costs.
Another problem of concern in many regions of the country is accumulation of moisture and/or harmful gases, such as radon, beneath homes and other structures. The accumulation of water beneath a floor slab can be a substantial problem, particularly where the water table is high or rainfall is plentiful. The accumulation of water beneath the slab of a structure can result in the seepage of water through the foundation and into the structure. In addition, the water is a breeding ground for microorganisms, such as mold and mildew, and may also cause the foundation to erode.
Radon is produced by the gradual decay of solid radioactive elements in the soil. While geographic regions that contain large concentrations of solid radioactive elements in the soil, the mere release of the gas even in these areas is not a concern in that the uninterrupted movement of radon into the atmosphere is generally at such a slow rate that little or no health hazard is posed.
The concern has risen in recent years due to the discovery of large concentrations of radon gas that had accumulated in dwellings. It became apparent that it was not the rate at which radon gas was given off by the soil, but the failure of dwellings to allow radon and other contaminants to continue on into the atmosphere. This has been caused by the effort of builders to make homes more energy efficient by thermally sealing the structures as tight as possible.
One factor in the degree of gas accumulation is the construction of the building itself and more specifically the construction of the support system in contact with the ground. That is, more and more homes are being built upon what is called a slab foundation. The effect of this type of foundation is to act as a cap to contain gases from the soil, allowing them to escape only when they find their way up into the house by the way of the cracks and plumbing openings formed in the slab.
Numerous subsurface ventilation systems have been proposed. However, like the prior art pesticide systems discussed above, these ventilation systems are susceptible to clogging, are relatively complex, and expensive to install. In addition, the prior art ventilation systems are not adapted to serve a dual purpose of periodically delivering pesticides beneath the structure.
To this end, a need exists for a subsurface pesticide injection and fluid extraction system which is simple in design, inexpensive to install, and easy to operate and maintain. It is to such a system that the present invention is directed.